1. Field of the Invention
The present invention relates to a sampling arm coupler. More particularly, the sampling arm coupler of the present invention is designed to attach a sampling arm to a lever arm, preferably on a vehicle, to facilitate collection of environmental samples. The sampling arm coupler has improved operational performance, maintenance and repair in cross-country terrain environments.
2. Description of the Related Art
Sampling arm assemblies have been used in military and civilian operations to test the environmental quality of a possibly contaminated area. The use of these assemblies allows area samples to be collected, retained and analyzed in a continuous operation over a large area. Samples from areas of possible nuclear, biological or chemical, commonly referred to as NBC, contamination may be gathered for testing for NBC agents. The assemblies obtain samples outside of a protective environment, such as a vehicle, with minimal exposure of personnel gathering the samples to the possible contamination. As this contamination may occur accidentally or purposely, samples need to be quickly and reliably collected over various geographical areas, including cross-country terrain.
Sampling arm assemblies have a lever arm which is joined to a sampling arm by a sampling arm coupler. The sampling arm coupler needs to provide stiff support to the sampling arm, and yet be flexible to withstand cross-country terrain operations. The sampling arm coupler also should be replaceable, separate and apart from the sampling arm and lever arm, to facilitate maintenance and repair.
Typically, the sampling arm coupler is part of an environmental sampling system which is attached to the rear end of a vehicle. As part of this sampling system, a lever arm is attached to a rotating servo motor on the vehicle. The lever arm is solid and approximately 18 inches long. Connected on the other end of the lever arm is a sampling arm, which is attached to the lever arm by the sampling arm coupler. The sampling arm is a solid flat piece approximately 2 feet long. Generally, the sampling arm has a wheel mechanism for carrying the sampling arm along the ground, while the sampling arm collects samples. Once the sampling arm collects a sample, the rotating servo motor lifts the lever arm and attached sampling arm up to a sensor on the vehicle. The sensor analyzes the collected sample for contamination. Once analyzed, the lever arm and attached sampling arm are lowered by the rotating servo motor to collect additional samples. Commonly, a sampling system has two or more separate lever arms on the back of the vehicle. This allows constant sampling, as one arm is positioned alongside the sensor, the other arm is collecting samples. Multiple arms also provide redundancy to the sampling system in case one arm is damaged.
The sampling arm coupler provides several functions. The coupler needs to ensure that the sampling arm does not detach from the lever arm. Additionally, the coupler needs to be designed and constructed to provide a strong and flexible attachment between the lever arm and sampling arm. Furthermore, the coupler needs to reliably place the sampling arm, once it is lifted, close to the sensor for proper analysis of the collected samples. This is preferably within a 10.degree. margin of error for misalignment. Alignment is also important to ensure that the two sampling arms do not crossover, thereby fouling the entire system. This is especially important because operational repair may expose operators to possible NBC contamination.
The reliability of testing an environmental sample is directly related to the quality of obtaining that sample. Fast response times are needed to obtain samples for testing which are analyzed quickly enough for preventive measures to be instituted. Rapidly moving a sampling system through a possibly contaminated area is especially useful to aid military operations. These military operations include personnel evacuations of non-combatants and medical assistance for populations exposed to NBC agents. In large area military operations, the sampling system is commonly moved to fully assess the size and location of a contaminated area. As the location of NBC contamination is usually uncertain, detection over cross-country terrain is an important capability.
Cross-country operations require sampling arm systems to function properly away from primary and secondary roads in cross-country terrain. Traveling across the cross-country terrain, the sampling arm system is continuously subjected to forces which may damage or break the sampling arm. As such, the system must withstand frequent deflections on rocks, or entanglement in vegetation as the vehicle travels over the cross-country terrain. Accordingly, the system needs flexibility to endure the repeated deflections, and structural resilience to maintain the proper structure to function properly.
When sampling arm systems are used in military operations, they must conform to military maintenance doctrines which ensure unified and reliable maintenance practices throughout the military. Strict military maintenance policy forbids certain practices, for example, soldiers are not permitted to use torque wrenches. Frequent changing of the sampling arm may be desired, however, in remote and dangerous environments. Commonly, however, couplers require a variety of bolts, machine screws, washer and nuts, tightened to a torque specification. Previously known sampling arm couplers may require up to fifteen bolts, washers and nuts, in the sampling arm assemblies. This complexity of previously known sampling arm couplers is problematical for maintenance personnel who have decreased manual dexterity when wearing NBC protective gear or in other difficult and adverse environmental conditions, such as snow, sand or loose dirt.
In view of the foregoing, improvements in sampling arm couplers have been desired. In addition to improved durability in cross-country terrain operations, it has been desired to provide sampling arm couplers which are easier to maintain and simpler to repair.
The present invention addresses these needs.